An automatic contour propagation method to follow parotid gland deformation during head-and-neck cancer tomotherapy.


We developed an efficient technique to auto-propagate parotid gland contours from planning kVCT to daily MVCT images of head-and-neck cancer patients treated with helical tomotherapy. The method deformed a 3D surface mesh constructed from manual kVCT contours by B-spline free-form deformation to generate optimal and smooth contours. Deformation was calculated by elastic image registration between kVCT and MVCT images. Data from ten head-and-neck cancer patients were considered and manual contours by three observers were included in both kVCT and MVCT images. A preliminary inter-observer variability analysis demonstrated the importance of contour propagation in tomotherapy application: a high variability was reported in MVCT parotid volume estimation (p = 0.0176, ANOVA test) and a larger uncertainty of MVCT contouring compared with kVCT was demonstrated by DICE and volume variability indices (Wilcoxon signed rank test, p < 10(-4) for both indices). The performance analysis of our method showed no significant differences between automatic and manual contours in terms of volumes (p > 0.05, in a multiple comparison Tukey test), center-of-mass distances (p = 0.3043, ANOVA test), DICE values (p = 0.1672, Wilcoxon signed rank test) and average and maximum symmetric distances (p = 0.2043, p = 0.8228 Wilcoxon signed rank tests). Results suggested that our contour propagation method could successfully substitute human contouring on MVCT images.

DOI: 10.1088/0031-9155/56/3/015
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@article{Faggiano2011AnAC, title={An automatic contour propagation method to follow parotid gland deformation during head-and-neck cancer tomotherapy.}, author={Elena Faggiano and Claudio Fiorino and Elisa Scalco and Sara Broggi and Mauro Cattaneo and Eleonora Maggiulli and Italo Dell'Oca and Nadia Gisella Di Muzio and Riccardo Calandrino and Gaetano Rizzo}, journal={Physics in medicine and biology}, year={2011}, volume={56 3}, pages={775-91} }